Electrode assembling in television projection tubes



C. C. LARSON Sept. 2, 1947.

ELECTRODE ASSEMBLING IN TELEVISION PROJECTION TUBES :s sheets;shamv 1 v'Filiaal Feb. 25, 1946 INVENTOR y CHRISTIAN C. LARSON ATTORNEY Sept- 2, 1947/ c. c. LARsoN 2,426,697

ELECTRODE ASSEMBLING IN TELEVISION PROJECTION TUBES FiledvFeb. 25, 1946 3 Sheets-Sheet 2 ATTORNEY Sept. 2. 1947- c. c. LARSQN 2,426,697

ELECTRODEASSBIBLING IN TELEVISION PROJECTION TUBES Filed Feb. 25, 194s :s sheets-sheet s FIGQS' INVENTOR 'CHRISTIAN C. LARSON ATTORNEY i e This invention relates y whichwapart atfle'astof an'` optical system is in- .l opticalsystemicr proj posed'..viewingscreen.=

Patented Sept. 2, 1947 .ELECTRODE ASSEMBLING IN TELEVISION PROJECTION TUBES Christian lC. Larson, Fort"`Wayne, Ind., assigner l i to Farnsworth Television & Radio Corporation,-v

corporatedfwithinethe "tube envelope, together particular reference Ato apparatus forl and a methvodof-z'aligningandi-assembling the components of -In .televisioni/systems, Tittiisjdesirablevto i upon acvlewing screen anjimagenfa-...televis'ion 'subject `having suitably large .dimensions 15o-permit viewing thereof u servers- Onefmeansffor. 1. thatha's..been. employed A television lmagegfongthei v-vreproducing toben-having Such ani-imagethen issenlaifgediby 'omersort of action upon a remotelydis Dna-opticaljsystem;which hasfoundxpartcularf onrecentlmis that employed Yin -thefso-called.- .ffSchmidt carriera?? yThis type of optical. system is preferred principally for of view, vwhereby to increase its light gathering property, andv is capable of projecting the light gathered from an optical'image onto a viewing screen with a 'minimum of distortion.

to.y a `television d tube in vwith theelectronic components thereofanditihas vthe reasonthatit affords a relatively wide angle Various organizations 'of apparatus have been l proposed to adapt the Schmidt optical system for use with a television tube, particularly a. reproducing tube. Essentially, this optical system constitutes three optical imaging components: the olltical surface upon which the initial image is formed,` a spherical reflecting surface which is mounted in spaced concentric relation to the optical surface and facing it, and, on the other side of the optical surface sind spaced therefrom, an aspherical corrector plate which optically is a refractive device. The corrector plate functions to compensate for the inherent spherical aberration of the reflecting surface.

One of the difficulties that has been encountered in adapting a reflecting optical system, such as that used in the Schmidt camera, when an attempt has been made to employ an opaque fluorescent screen, has been the non-uniform distortion produced in transmitting the light from an opaque screen through the angularly disposed Walls of the tube envelope. Primarily, by reason of this difficulty, most attempts to employ a fluorescent optical surface which is opaque have been abandoned in favor of a translucent fluorescent screen formed on one end of the tube envelope. The reflecting mirror of the Schmidt system may then be located externally of the tube in such a manner that it faces the tube screen. Such an .a corporation of Delaware 1 YinnilicauenFebruary 2,5. 1946, Serial No. 650,070

` 1o claims. loi. 31e- 29) rrangement, however, does not operate at maxivmum efficiency by reason of the loss of light due to transmission .through the screen.

; One expedient which has been used effectively to permit the employment of an opaque fluorescent screen in a tube adapted to function in conjunction with a reflecting optical system is the rvdeviceV disclosed in a copendingl application of Madison Cawein Serial No. 489,869 filed 'June 5, L10 izable; group of vola- 1.

mplishingthisbbject formati n-ofi the 1,9513; and entitled Electron optical device. In

vjthistube the spherical reflecting `mirror is ,mounted within rvthetube envelope and-theopposite end wall of the tube is either made optically plane and the corrector plate mounted externally of the plate or this end wall is constituted -b'y the corrector plate. In order for such'a tube to function'electronically, it is, of course, necessary that thevelectrodes be` enclosed Within a highly evacuated envelope. Also for such a device to function satisfactorily optically, it is essential that the optical imaging components including the optical surface be located in the tube with a high degree of Aprecision in its relationship to the reflecting member and to the corrector plate. It is exceedingly difficult, if not practically impossible, to position the optical surface of the tube with the re- ,quired precision by means of jigs or the like. At present, the best known system for mounting the electrode in the tube is to employ optical means, such as suitably projected light, while the tube is still in the process of formation and before it is. evacuated.

It is the object of the present invention, therefore, to provide apparatus for and a method of assembling and mounting the electronic and optical imaging components of a device in which both types of components are located Within a tube envelope.

In accordance with' this invention, the method for aligning and mounting the focal surface member in a tube envelope which also contains a refleeting member comprises the following steps: The focal surface member is inserted in the tube envelope so that it faces the reflector; a light pattern is projected onto the focal surface member so that the light rellected therefrom is successively reflected by said reflector and refracted by a corrector plate and then is directed onto a viewing screen. The focal surface member and the corrector plate are then individually adjusted relative to one another and to th'e reflector to produce the best imagev of the light pattern on the .viewing screen. Finally. the focal surface member is rigidly sealed'in its adjusted position to the tube envelope.

According to a preferred form of apparatus for performing the described method of the invention, there is provided a bed which may include a pair of parallel ways, and upon which there is mounted a plurality of carriages. The optical imaging components which are to be assembled in the vacuum tube envelope are mounted respectively on these carriages. In a tube which is to embody an optical system corresponding generally to that of the Schmidt camera, the optical imaging components comprise the focal surface member, a reflecting member and a refractive corrector plate. There also is provided means for projecting an optical image onto one of the imaging components which, in the case of the Schmidt system, may be the focal surface member. A viewing screen also is provided and the apparatus additionally includes means for moving at least one of the carriages with respect to th'e bed and to at least one other of the carriages for the purpose of reproducing on the viewing screen a substantially exact replica of the optical image. Having adjusted the optical imaging components in this manner, facilities are provided for permanently sealing one of the imaging components in the tube in its adjusted position relative to at least one other of the components.

For a better understanding of the invention together with other and further objects thereof, reference is made to the following description, taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is a side elevational view, partly in section, of apparatus embodying the invention;

Fig. 2 is a fragmentary view to an enlarged scale of the focal surface member showing in detail one means for supporting it for alignment within the tube envelope;

Fig. 3 is a plan view of the apparatus;

Fig. 4 is a traverse sectional view taken on the line 4-4 of Fig. l; and

Fig. 5 is a traverse sectional view taken on the line 5-5 of Fig. l.

Having reference now to the drawings, there will be described a preferred form of apparatus embodying the instant invention for carrying out the novel method of the invention. Generally, this apparatus resembles a lathe. It consists of a bed II, supported by legs I2 and I3. The upper portion of the bed Il is divided to form two parallel ways I4 and I5. I

Adjacent one end of the bed I I a head-end carriage I6 is mounted on the ways I4 and I5 and in this embodiment of the invention is securely attached thereto.v There also is provided a tail-end carriage I1 similar in structure to the head-end carriage but mounted on the lathe bed in such a manner that it faces in the direction opposite to that in which the head-end carriage faces. The tail-end carriage is supported on the ways I4 and I5 so that it may be slidably moved thereover in a direction longitudinal of the lathe bed. In order to eiect this movement of the tail-end carriage, there is attached to one side thereof a lead screw follower I6. This follower is provided with an internal thread for engagement with a lead screw I9. The lead screw is mounted along the front side of the lathe bed II and is supported at its opposite ends by bearings 2I and 22 rigidly attached to the lathe bed. At the left hand end of the lead screw as viewed in Fig. 1, there is provided a hand wheel 23 which may be turned to impart rotation to the lead screw.

ment with a lead screw 26 which extends along the back side of the lathe bed as shown in l'lig.` 3. The rear longitudinal lead screw 26 issupl ported adjacent to ends in bearings 21 and 28,

which are rigidly attached to the side of the lathe the screw 49.

bed. At the left hand end of the rear lead screw 26 there is attached a hand wheel 29 for imparting rotative movement tothe screw. As shown best in Fig. l, the carriage 24 is provided on i-ts upper surface with a dovetail projection 3I. This projection is adapted to engage a dovetail slide formed in the underside of a superstructure member 32 so that this member may be slidably moved transversely of the lathe bed. The superstructure 32 is provided with a depending feed screw follower 33 (Fig. 5) This follower is internally threaded and adapted to engage a feed screw 34 which extends transversely of the lathe bed and is suitably journaled in the carriage 24. 'Ihere is attached to the outer end of the feed screw 34 a single crank 35 by means of which the feed screw may be rotated.

In a similar manner there is provided on the` superstructure 32 a cooperating dovetail projection and slide extending perpendicularly to the top of the lathe bed. As best illustrated in Fig. 5, a support 36 is affixed to one of these dovetailing members. A feed screw follower 31 is attached to the other of these dovetailing members and is internally threaded for engagement with a feedscrew 38. This feed screw is mounted in the superstructure 32 perpendicularly to the lathe bed and has attached to its extending end a double crank 39 by means of which the feed screw may be rotated.

The construction of the head-end carriage I6 and the tail-end carriage I1 is generally similar. Fig, :4 shows a face view of the tail-end carriage. the upright portion of the carriage which extends perpendicularly to the bed II is circular and is provided with a plurality of thumb screws, such as 4 I, 42 and 43 spaced approximately at 120 degree angles relative to one another around the carriage, The central portion of the upright carriage section is provided with a circular opening 44 into which is set an annular split sleeve 45. This sleeve may be made of wood or some other equivalent material. The inside of the sleeve 45 is provided with an annular groove 4G, best illustrated in Fig. l. The sleeve 45 preferably is made somewhat smaller in diameter than the circular opening 44. The thumb screws 4I, 42 and 43 are threaded through a. convenient portion of the carriage so that the ends thereof engage the outer peripheral edge of the sleeve 45.

The head-end carriage I6 is provided with a collar 4l which extends at right angles from the face of the carriage.l Inside of this collar is mounted a split sleeve 48 similar in material to the tail-end sleeve 46. `Also the carriage is provided with a plurality of thumb screws suchas These thumb screws are spaced around the vertical section of the carriage in a substantially similar manner to the corresponding thumb 'screws of the tail-end carriage I'I. The ends of the head-end thumb screws, such as 49, are adaptedv to engage the outer peripheral surface of the sleeve 48, which preferably is made somewhat smaller in diameter than the inside diameter of the collar 41.

The auxiliary carriage support 36 supports a rod 50 (see Figs. 3 and 5) which extends perpendicularly from the support across the bed Il of the apparatus. There also is affixed to the rod 56, either rigidly or adjustably as by a clamp coupling I, a second rod 52 which is an elongated member and extends longitudinally of the bed il in the direction of the carriage I1. The outer end of the elongated rod 52 is provided with a hole 53 (see Fig. 2) which is drilled into the end of the rod for a purpose to be described.

In using the described apparatus for the purpose of aligning the focal surface member in a tube of the character described, the tube blank is mounted in the head-end carriage I6. In one form of lthe tube, it cmprises a main bodyV portion 54 which at one end is formed into a plane optical window 55 disposed substantially at right angles to the long axis of the tube. On the inside of the wall of the main body portion of the 'tube opposite to the window 55 there is provided a concave reflector 56. As illustrated, this end wall of the tube is spherically shaped and the reflector 56 is mounted directly thereon. It, however, is contemplated that other forms of tubes may be employed within the scope of this invention wherein, for example, the reflector '56 is separately supported with the body portion 54 of the tube in spaced relation to the end walls thereof. The reflector 56 has a central opening formed therein which is in register with a relatively long tubulation 51 extending from the main tube body 54. This tubulation is for the purpose of housing suitable electronic apparatus for cooperating with the focal surface member when the tube is completed. At this stage,I of the construction of the tube, the outer end of the tubulation 51 is open to the atmosphere. A relatively short stem 5B is formed so that it extendsoutwardly along the central axis of the tube from the window 55.

The tube envelope as described is inserted in` the split sleeve 48 and the plurality of thumb screws such as the screw 49 are tightened to deform the sleeve sufficiently to securely grip the tube body 54. In this manner, the tube envelope attached thereto in is rigidly secured to the head-end carriage I6 l substantially in the manner illustrated in Fig. 1.

The next step in the formation of the tube is to insert the focal surface member. The general character of this member is illustrated best in Fig. 2 of the drawings. The focal surface member 59 has a generally convex spherical configuration. It is mechanically and electrically mounted on the end of a lead 6I which is disposed substantially at the center of the electrode. The lead 6I is sealed into one end o-f a small glass tubular member 62 which at the outer end thereof is provided with a flared portion 63. The lead 6I extends through the member 62 for some little distance beyond the flared end thereof.

The elongated rod 52 is detached from the supporting rod at the coupling 5| sothat it may be attached temporarily to the focal surface supporting structure. As shown in Fig. 2, the outer end of the rod 52 is o-f slightly smaller external diameter than the internal diameter of the tubular member 62. First, there is wrapped around the end of the rod 52, a layer of material 64 such as asbestos for example. The wrapping 64 then is moistened and the end of the rod 52 inserted into the tubular member 62 in somewhat the position shown.

The rod 52 with the focal surface member 59 the manner described, then is ready for insertion in the tube. Before Athis step is taken, however, the corrector plate for the optical system is mounted in the tail-end carriage I1. The corrector plate 65 is inserted in the split sleeve 45 in such a manner that the peripheral edge thereof lies within the annular groove 46. The corrector plate is secured in the mounted sleeve by tightening the thumb screws 4l, 42 and 43.

The tail-end carriage I1 then is moved longitudinally of the bed Il to substantially the position shown in Fig. l. 'I'he rod 52 then is inserted through the tubulation 51, out through the stern 58 and through a centrally disposed aperture 66 formed in the corrector plate 65 and is then attached to the supporting rod 50 by means of the coupling 5|. At this stage, the tube containing the reflector I56, the focal surface member 59 and the corrector plate 65 are located approximately in the desired relative positions.

A light projector 61 then is mounted by suitable means (not shown) to project a light pattern through the tubulation 51, onto the focal surface member 59. Adjacent the other end of the apparatus, there is mounted a viewing screen 68 in alignment with the longitudinal axis of the optical system. An optical image is projected onto the focal surface member 59 from the projector 61 and may be of any desired character. For example, it may be a conventional test pattern used generally in television systems. The light reflected from the focal surface member 59 representative of the optical image is directed onto the spherical surface of the reector 56 and then is transmitted through therefractive corrector plate 65 for ultimate projection onto the viewing screen 68. The manner in which the optical system functions may be determined by an observation'reproduced `by the optical image on the screen 68. The apparatus then is adjusted in a manner to be described to project the image onto the screen 68 to produce the best possible result.

In order for the optical system to function in the manner desired, itis ,necessary that the focal surface member 59 be located within the tube body 54 so that it is concentric with the surface of the reflector 56. The` corrector plate 65 must also be located at the proper distance from the reflector 55. It also must be positioned to be in substantial coaxial alignment with the focal surface member 59 and the reflector. The spacing between the focal surface member, the reflector, the corrector plate and the screen 68 must bear a definite relationship to themagniflcation desired. In making the necessary adjustment to achieve this spacing, the head-end carriage I6 is permanently located on the bed Il. Consequently, the reflector 56 is xed in position. Also, in accordance with the desired focal distance of the system, the screen 68 is located permanently at a predetermined distance from the reflector 56. The spacing of the corrector plate 65 is adjusted by moving the tail-end carriage I1 under the control of the lead screw I9 effected by suitable manipulation of the hand Wheel 23. The spacing of the focal surface member 59 is similarly adjusted by moving the auxiliary carriage 24 under the control of the lead screw 26 effected by suitable turning of the hand wheel 29.

The axial alignment of the corrector plate is adjusted by means of the thumb screws 4|, 42 and 43. By'a suitable manipulation of the screws,

the corrector plate may be moved both trans- I versely of and perpendicularly to the bed l l The axial alignment of the focal surface 59 is effected by suitable manipulation of the superstructure 32 and the mounting plate 36 of the auxiliary carriafge 24. Transverse movement of the focal surface relative to the bed H is effected by a manip-M ulation of the single crank 35 whereby the superstructure 32 is moved across the bed. Vertical movement of the focal surface member is effected by the proper manipulation of the double crank 39 whereby the mounting plate 36 is moved perpendicularly to the bed.

All of these adjustments are made while viewing the optical image projected onto the screen `In this manner there may be made an airtightv joint between the tubular member 62 and the stem 58. The rod 52, then may be detached from the tubular member 62 by a combined twisting and pulling action. The focal surface member 59 as a result will be rigidly mounted in the tube at the proper distance from the reiiector 56 and in coaxial alignment therewith.` The tube then may be demountedvfrom the apparatus for. the insertion of the electronic structure in the tubulation 51 thereof and for the sensitization ofv the convex surface of the focal surface member, after which the envelope may be evacuated and sealed in the usual manner.

The foregoing description of a preferred formv of the invention has considered only the attachment of the focal surface "member 59 to the tube envelope. It may be desirable in the fabrication of tubes of this character to make ythe corrector plate 65 a part of the tube. In such a case, it is possible to dispense with the plane window 55 and to substitute for it the corrector plate located, of course, at the proper distance from the redector 56. It is contemplated to'be within the scope of .the present invention to employ similar apparatus and substantially the same method for the production of a tube of this character. After the proper alignment of the components of the system, it is merely necessary to fuse the peripheral edge of the corrector plate, such as the plate 65, to the circumferential walls of the tube body 54 in addition to fusing the equivalent of the tubular member 62 to the tube envelope. In such a case, it may be preferable to use an apparatus such as that desired set up vertically instead of horizontally as herein illustrated and described.

It will be obvious to those skilled in the art that the described apparatus may also be employed for assembling a vacuum tube having a plurality of optical imaging components where the optical system is something different than the system of the Schmidt camera.. For example, the optical system may consist only of a focal surface member and either a reflector or a refraction device such asa lens. Each of two such components may be mounted respectively on carriages supported by a bed. One or both carriages may be I'moved relative to the other in order properly to align the imaging components. In such a case,

when the proper adjustment has been eifected whereby a good reproduction'of the optical image is projected onto the viewing screen, the two components may be securely fastened relative to one another such as by sealing yboth of them to a tube envelope.

Throughout the foregoing description and in the appended claims, the term focal surface member is used. The present specification kconsists specifically of a projection reproducing tube.

This treatment of the invention, however," is iii-' tended vto be illustrative only. It obviously is within the scope of this invention to employ the same apparatus and method for the production of a television tube of the image analyzing type, such as is used in conjunction with transmitting apparatus. The onlydifl'erence between the two types of tubes as far as present considerations are concerned is in the character of-.the focal surf face member and the electronic apparatusfused in conjunction therewith.` For a .rei'iroducingl tube, the focal surface memberjWiILhaVe formed* thereon a fluorescent screen f or bombardment by a stream of electrons .from an 'electron'fgun mounted in the tubulation -51 in ,orderl to' produce an opticalv image for projection onto the viewing screen. In the case of an .image analyzing'tube, the focalsurface member will .be conditioned'to" produce photo-electric effects in response 'to theL i projection thereon of an opticalA image 'which is-v to be converted in a train of sgn'alsrepresenta# tive thereof by suitably scanning theN resultant electron image byconrventional means located 'in the tubulation 51.

, While there` has been describedwhatgat present, is considered the preferred embodiment of` the invention, vit will be obvious to those skilled in the art that various changes andv modifications may be made therein without departing from the invention, and it, therefore, is aimed inthe appended claims to cover all such changes --and modifications as fall within the true spirit and scope of the invention. l

What is claimed is; v v

1. In apparatus for assembling a vacuum tube having` a plurality of optical imaging components incorporated therein, a bed, a plurality of car'- riages mounted on said bed for supporting respectively said imaging components, means for projecting an optical-'image onto one-of said components, a viewingscreen, means for moving one of 'said carriages withrespect to said bed andto another of said carriages, whereby to effect the reproduction on said viewing screen ofj a substantially exact replica of said optical image, and

means for permanently sealing one of said imaging components in said tube in its adjusted position relative to others of said components.

2. In apparatus for assembling a vacuum tube having a. plurality of optical imaging components incorporated therein, a bed, a fixed carriage mounted on said bed for supporting one of said imaging components, a movable carriage mounted on said bed for supporting another of said imaging components, means fory projecting an optical image onto one of said components, a viewing screen, means for moving said movable carriage on said bed, whereby to effect the reproduction on said viewing screen of a substantially exact replica of said optical image, and means for permanently sealing one of said imaging components in said tube in its adjusted position relative to the other of said components.

3. Apparatus for assembling a vacuum tube having a plurality of optical imaging components incorporated therein comprising, a bed having a pair of parallel ways, a fixed carriage mounted on said bed for supporting one of said imaging components, a plurality of movable carriages mounted on said bed for supporting respectively others of said imaging components, means for projecting an optical image onto one of said components, a viewing screen, means for independently moving said movable carriages with respect to said bed and to one another, whereby to effect the reproduction on said viewing screen of a substantially exact replica of said optical image, and means for permanently sealing one of said imaging components in said tube in its adjusted position relative to others of said components.

4. Apparatus for locating a focal surface member in the envelope of a television tube having incorporated therein a spherical reflector comprising, a lathe bed having a pair of parallel ways, a fixed carriage mounted on said ways for rigidly supporting the tube envelope, a movable carriage mounted on said ways in an opposingposition to said fixed carriage, means for moving said movable carriage longitudinally on said ways, a corrector plate adjustably mounted on said movable carriage adjacent said envelope in such manner that said corrector plate may be moved both transversely and perpendicularly to said lathe bed ways, an auxiliary carriage mounted on said lathe bed ways and adapted for movement longitudinally of said Ways, a superstructure mounted on said auxiliary carriage and adapted for movement on said auxiliary carriage transversely of said lathe bed ways, a sliding support mounted on said superstructure and adapted for movement perpendicularly to said lathe bed ways, and a support attached to said sliding member and extending into said envelope for supporting said focal surface member within said tube envelope.

5. Apparatus for locating a focal surface member in the. envelope of a television tube having incorporated therein a spherical reflectorv comprising, a lathe bed having a pair of parallel ways, a fixed carriage mounted on said ways, means for rigidly mounting the tube envelope on said xed carriage, a movable carriage mounted on said ways in an opposingl position to said fixed carriage, means for moving said movable carriage longitudinally on said ways,.means for adjustably mounting a corrector plate on said movable carriage adjacent said envelope in such a manner that said corrector plate may be moved both trnsversely and perpendicularly to said lathe bed ways, an auxiliary carriage mounted on said lathe bed ways and adapted for movement longitudinally of said ways, a superstructure mounted on said auxiliary carriage and adapted for movement on said auxiliary carriage transversely of said lathe bed Ways, a sliding support mountedon said superstructure and adapted for movement perpendicularly to said lathe bed ways, and a. supporting member attached to said sliding member and extending into said envelope for adjustably supporting said focal surface member within said tube envelope.

6. Apparatus for locating a focal surface member in the envelope of a television tube having incorporated therein a spherical reflector comprising, a lathe bed having a pair of parallel ways, a head-end carriage mounted on said Ways, a first supporting structure attached to said head-end carriage for rigidly mounting the tube envelope on said head-end carriage, a tail-end carriage mounted on said ways in an opposing position to said head-end carriage, means for moving said tail-end carriage longitudinally on said ways, a second supporting structure attached to said tailend carriage for mounting a corrector plate adjacent said envelope opposite to said reflector,

means embodied in said tail-end carriage for adjustably holding said corrector plate in said second supporting structure in such a manner that said corrector plate may -be moved both transversely and perpendicularly to said lathe bed ways, an auxiliary carriage mounted on said lathe bed ways, means for moving said auxiliary carriage longitudinally of said waysy a superstructure mounted on said auxiliary carriage, means for moving said superstructure on said auxiliary carriage transversely of said lathe bed ways, a sliding support mounted on said superstructure, means for moving said sliding support perpendicularly to said lathe bed ways, and a stiff supporting member attached to said sliding member and extending longitudinally of said lathe bed ways to the interior of said envelope, said supporting member being provided with facilities at its extended end for supporting said focal surface member.

7. Apparatus for locating a focal surface member in the envelope of a television tube having incorporated therein a spherical reflector comprising, a lathe bed having a pair of parallel ways, a head-end carriage mounted on said ways and having a portion extending substantially perpendicularly upward from said ways, a first supporting structure attached to said head-end carriage for rigidly mounting the tube envelope in such position that an open tubulation formed in the tube wall opposite to said reflector extends outwardly from said head-end carriage in a direction substantially parallel to said ways, a tail-end carriage mounted on said ways in an opposing position to said head-end carriage, means including a first lead screw for moving said tail-v end carriage longitudinally on said ways, a second supporting structure attached to said tailend carriage for mounting an aspherical refractive corrector plate adjacent said envelope tubulation, said corrector plate having an aperture mounted substantially in alignment with said tubulation, means including a plurality of thumb screws threaded into said tail-end carriagefor adjustably holding said corrector plate in said second supporting structure in such a manner that said corrector plate may, by manipulation of said thumb screws, be moved both transversely and perpendicularly to said .lathe bed ways, an auxiliary carriage mounted means including a second lead screw for moving said auxiliary carriage longitudinally of said ways, a superstructure mounted on said auxiliary carriage, means including a third lead screw for moving said superstructure on said auxiliary carriage transversely of said lathe bed Ways', a sliding support mounted on said superstructure and adapted for movement perpendicularly to said lathe bed ways, a fourth lead screw for effecting saidl perpendicular movement of said sliding member, and a rod attached to said sliding member and extending longitudinallyof said lathe bed ways through the aperture in said corrector plate and the open tubulation of said envelope, said rod being provided with facilities at its extended end for supporting said focal surface member within said tube envelope.

8. Apparatus for locating a focal surface member in the envelope of a television tube having incorporated therein a spherical reflector comprising, a lathe bed having a pair of parallel ways, a head-end carriage mounted in xed position on said ways and having a portion extendmg substantially perpendicularly upward from said ways, a rst clamping structure attached to the lon said lathe bed ways,

1l upright portion of said head-on carriage for rigidly mounting the tube envelope in such position that an open tubulation formed in the tube Wall opposite to said reflector extends outwardly from said head-end carriage in a direction substantially parallel to said Ways, a tail-end carriage mounted on said Ways in an opposing position to said head-end carriage, means including a rst lead screw for moving said tail-end carriage longitudinally on said Ways, a second clampingr structure attached to said tail-end carriage for mounting an aspherical refractive corrector plate adjacent said envelope tubulation, said corrector plate having an aperture mounted substantially in alignment with said tubulation, a plurality of thumb screws threaded into said tail-end carriage and spaced around the periphery of said second clamping structure for adjustably hold` ing said corrector plate in said second clamping structure in such a manner that said corrector plate may, by manipulation of said thumb screws, be moved both transversely and perpendicularly to said lathe bed ways, an auxiliary carriage mounted on said lathe bed ways, means including a second lead screw for moving said auxiliary carriage longitudinally of said Ways, a superstructure mounted on said auxiliary carriage, means including a third lead screw for moving said superstructure on said auxiliary carriage transversely of said lathe bed ways, a

sliding support mounted on said superstructure 12 member in the envelope of a television tube together with a spherical reflector comprising the steps of, rigidlysupporting said reflector in the tube envelope, adjustably supporting said focal surface member within said tube envelope, ad-

,justably supporting a refractive corrector plate external of said tube envelope, projecting a light pattern' on said focal surface member, individually adjusting the positions of said focal surface member and said corrector plate to produce a substantially undistorted image of said light pattern in a predetermined focal plane, and sealing said focal surface member to said tube envelope in its adjusted position.

10. The method of mounting a focal surface member in the envelope of'a television tube having incorporated therein an apertured spherical reflector comprising the steps of, rigidly supporting the tube envelope and the incorporated reflector, adjustably supporting an apertured refractive corrector plate external of said tube envelope, adjustably supporting said focal surface member within said tube envelope through the aperture in said corrector plate, projecting' a light pattern on said focal surface member through the aperture in said reflector, individually adjusting the positions of said focal surface member and said corrector plate to pro-v duce a substantially undistorted image of said light pattern in a predetermined focal plane, and

sealing said focal surface member to said tube envelope in its adjusted position.

- CHRISTIAN C. LARSON.

REFERENCES CITED A The following references are of'record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,705,356 Bohner Mar. 12, 1929 2,154,500 Elmendoif Apr. 18, 1939 2,324,449 Westerlund July 13, 1943 

